1) Field of the Invention
The present invention relates to a technique for preparing design data of a structure to be used by CAD (Computer Aided Design). Particularly, the present invention relates to a technique for newly adding information about a component to design data of a structure.
2) Description of the Related Art
Heretofore, components [for example, screw, bolt, nut, connector, electronic component (for example, LSI (Large Scale Integration) chip); hereinafter, referred to as library components], which have general-purpose properties and are used in common in design of various products (structures), are generally purchased as ready-made goods and used. However, there often occurs a case where real things of the library components exist but do not exist as shape information (CAD data) used in design.
In design of a product, it is general to define a shape of a component or assembly of a product by referring to the library components, it is thus necessary that shape information about each of the library components are included in design data (hereinafter, referred to as CAD data) of a product.
For design verification in a stage before a prototype is manufactured, it is necessary that the library components exist in CAD data as shape information usable in the verification.
For this reason, shape information (non-CAD data) may be obtained from a real thing of a library component by using a 3D (Three-Dimensional) scanner, and the shape information in a form different from that of the obtained CAD data may be used in design or verification.
As 3D scanners, there are some types, one of which measures a surface of a component in various ways and represents a shape of the component with groups of points obtained in the measuring, another of which represents a shape of a component by surfaces obtained by connecting adjacent point groups after the point groups are obtained, and so on.
Other than the technique using a 3D scanner, it is considered that when shape information in a form, which is different from that of CAD data, about a library component is obtained from a distributor of the library component, the obtained shape information is used in design or in verification.
In order to facilitate design of a structure, there has been proposed a technique that inputs data relating to attributes or shape features of a required component, and retrieves a similar standard component or a similar example component from a database of standard components in which the attributes of a required specification and parametric dimensions of CAD are continuously corrected by restrictions, or a database of example components prepared in the past (refer to a Patent Document 1 below, for example).
As another technique using a three-dimensional shape of an object, there has been proposed a technique that performs collation determination using a three-dimensional shape or reflectivity of a surface of an object to be collated when the object is collated by using an image (refer to Patent Document 2, for example).
However, shape information or the like obtained by a 3D scanner is not in a form unusable in CAD but in a form in which information necessary in CAD (for example, reference surface or coordinate system) is undefined (is not included), although it represents a shape. Therefore, the shape information or the like obtained by a 3D scanner is difficult to be used as it is in actual design (CAD) as shape information representing a shape of a component.
In the case where it is expressed that a certain surface of a library component is matched with a surface of another component, it is impossible to define that the surface of the library component is matched with the surface of another component because the shape information does not include “surface” that is defined in CAD data when shape information of the library component obtained by a 3D scanner is point group data.
When shape information of a library component obtained by a 3D scanner represents a shape formed by a surface made by connecting adjacent point groups, a surface, which is originally flat, does not often become a flat surface because of error or the like in measurement. In such case, a definition that a certain surface of a library component is matched with a surface of another component is extremely difficult.
To use shape information representing a shape of a component in CAD, presence of a virtual reference surface or coordinate system, which that does not exist as a shape of the component, is important for the shape information. But, such definition is not included in the shape information or the like obtained by a 3D scanner.
As above, even if information or the like obtained by a 3D scanner is included in CAD data, it is impossible to generate CAD data to be used in design or in verification by using such information or the like.
Heretofore, even when shape information about a library component that the designer (operator) desires to add to CAD data of a product is read by a 3D scanner, the designer (operator) has to newly prepare, manually, shape information (for example, CAD data itself) in a form usable in CAD about the library component while confirming a shape or specification of the library component, and add it to the CAD data of the product.
Accordingly, much work or a number of steps of the work are heretofore required to newly add shape information about a library component to CAD data.
Even in the above-mentioned technique disclosed in Patent Document 1, the designer has to directly input data relating to attributes or shape features of a library component while referring to information or the like obtained by reading the library component by a 3D scanner, or specification information about the library component, which leads to an increase in labor or an increase in the number of steps of the work.
[Patent Document 1] Japanese Patent Laid-Open No. HEI09-179892
[Patent Document 2] Japanese Patent Laid-Open No. 2002-157595